1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a heat curing device for curing a sealant.
2. Discussion of the Related Art
Among ultra-slim flat panel displays having a display screen whose thickness is merely several centimeters, a liquid crystal display device (LCD) has the advantage of a low operation voltage, resulting in low power consumption, and portability. Accordingly, the LCD can be widely used in a variety of applications, such as notebook computers, monitors, spacecraft and aircraft instrumentation.
Hereinafter, a related art LCD device will be described.
As shown in FIG. 1, the related art LCD device includes a lower substrate 1 and an upper substrate 3 opposing each other. Although not shown, the lower substrate 1 includes a thin film transistor and a pixel electrode, and the upper substrate 3 includes a light-shielding layer, a color filter layer, and a common electrode.
A liquid crystal layer 5 is formed between the substrates 1 and 3. The liquid crystal layer 5 is sealed between the substrates 1 and 3 by a sealant 7 formed between the substrates 1 and 3.
The aforementioned related art LCD device may be fabricated using a liquid crystal injection method or a liquid crystal dropping method.
When the liquid crystal injection method is used, after a lower substrate and an upper substrate have been prepared, a sealant having an injection hole is formed on one of the substrates. After the upper and lower substrates are bonded to each other using the sealant, liquid crystal is injected through the injection hole to form a liquid crystal layer, completing the LCD device.
When the liquid crystal dropping method is used, after a lower substrate and an upper substrate are prepared, a sealant having no injection hole is formed on one of the substrates. A liquid crystal layer is formed by dropping a liquid crystal onto one of the substrates, after which the substrates are bonded to each other, to complete the LCD device.
In the liquid crystal injection method, a relatively long time is required for injecting liquid crystal, particularly when forming large sized LCD cells. Using the liquid crystal dropping method may increase productivity when producing large sized LCD devices.
In both the liquid crystal dropping method and the liquid crystal injection method, substrates are bonded to each other after forming a sealant. A process for curing the sealant may be used with either method for forming the liquid crystal layer.
In the liquid crystal injection method of the related art, a thermosetting sealant is used as the sealant, and a heating process for curing the sealant is used. With the liquid crystal dropping method of the related art, ultraviolet (UV) radiation is used as the primary agent for curing the sealant. However, because of difficulties in achieving a complete cure of the sealant using UV rays, a heat curing process may be carried out along with the UV curing process.
Accordingly, a heating process for curing the sealant may be required with either the liquid crystal injection method or the liquid crystal dropping method. A heat curing device is used to carry out the heat curing process.
FIG. 2 is a sectional view illustrating a related art heat curing device for curing a sealant.
As shown in FIG. 2, a heat curing device of the related art includes a chamber 10 and a support 12 for supporting a substrate 14 in the chamber 10. A plurality of liquid crystal cells are formed at the center of the substrate 14. Active regions of the liquid crystal cells may be damaged if the support 12 is in contact with the center of the substrate 14. In order to prevent the active regions from being damaged, the support 12 is formed to contact the substrate 14 only at the substrate ends.
Large sized substrates are increasingly used in the manufacture of liquid crystal display devices. However, as shown in FIG. 2, when supporting large substrates in the related art curing device, the substrate 14 may sag in the center under its own weight if the support 12 contacts only the ends of the substrate 14.